Research in the area of allergic reactions of the lung has provided evidence that arachidonic acid derivatives formed by the action of lipoxygenases are related to various disease states. Some of these arachidonic acid metabolites have been classified as members of a family of eicosatetraenoic acids termed leukotrienes. Three of these substances are currently thought to be major components of what has been previously called slow reacting substance of anaphylaxis (SRS-A).
Leukotriene B.sub.4 (LTB.sub.4) is a proinflammatory lipid which has been implicated in the pathogenesis of psoriasis, arthritis, chronic lung diseases, inflammatory bowel diseases, and other inflammatory states characterized by the infiltration and aggregation of polymorphonuclear leukocytes. Thus aggregated, the polymorphonuclear leukocytes liberate tissue-degrading enzymes and reactive chemicals causing the inflammation. Antagonism of LTB.sub.4 should therefore provide a novel therapeutic approach to treatment of these conditions.
Similarly, antagonists of leukotriene D.sub.4 (LTD.sub.4) have been indicated for treating conditions characterized by the excessive release of LTD.sub.4, including immediate type hypersensitivity reactions such as asthma and shock.
It is the object of this invention to provide novel chemical agents which are selective leukotriene antagonists that can be used therapeutically in the treatment of inflammation and allergic disorders such as asthma, where leukotrienes are thought to be causal mediators.